[stable-2.9] ansible-test - add constraint for virtualenv (#67289)

* ansible-test - add constraint for virtualenv

* Limit virtualenv only on macOS.

Co-authored-by: Matt Clay <matt@mystile.com>
(cherry picked from commit 8f296a6533)

Co-authored-by: Sam Doran <sdoran@redhat.com>

changelogs/fragments/ansible-test-constraints-virtualenv.yml

@@ -0,0 +1,2 @@
+bugfixes:
+  - ansible-test - Use ``virtualenv`` versions before 20 on provisioned macOS instances to remain compatible with an older pip install.

test/lib/ansible_test/_data/setup/remote.sh

@@ -73,7 +73,7 @@ elif [ "${platform}" = "rhel" ]; then
 elif [ "${platform}" = "osx" ]; then
     while true; do
         pip install --disable-pip-version-check --quiet \
-            virtualenv \
+            'virtualenv<20' \
         && break
         echo "Failed to install packages. Sleeping before trying again..."
         sleep 10